Avalanche Forecast

Issued: Jan 24th, 2016 7:52AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Persistent Slabs and Wind Slabs.

pmarshall, Avalanche Canada

Northwest Coastal.

Monday could be the calm before the storm(s). Regardless, it is still a day to exercise constraint and conservative decision-making.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Monday: Mainly cloudy with light snow – 2-5 cm. The freezing level is around 1000-1400 m. Winds are moderate or strong from the S-SW. Tuesday: Periods of snow or rain – 10-20 mm/cm. The freezing level climbs to 1200-1500 m and winds remain strong. Wednesday: More rain or snow – possibly very heavy. The freezing level could jump to 2000 m and winds will keep blasting from the South.

Avalanche Summary

Explosives control on Saturday produced numerous slab avalanches up to size 3. Most of these failed on the mid-January surface hoar and some stepped down to the Boxing Day surface hoar layer. One observer also viewed numerous size 3 natural slabs on a variety of aspects, but these may have been a day or two old.

Snowpack Summary

Light snowfall and steady moderate S-SE winds continue. Expect fresh wind slabs overlying older wind-affected surfaces in exposed lee and cross-loaded terrain. The January 9th surface hoar/facet layer down 60-80 cm in most places, and seems most concerning at and below treeline. Recent snowpack tests give moderate "pops" results on this layer. Approximately 10 cm below this weakness you might find the Dec. 26/31 surface hoar layer. Reports of remote triggering, whumpfing, and sudden shears in snowpack tests are all indications that both these layers could propagate well if triggered. Deeper persistent weaknesses buried in December have the potential to wake-up to heavy loading, rapid warming, or avalanches stepping-down.

Problems

Persistent Slabs

Buried surface hoar, now 60 cm deep on average, is primed for triggering. It's possible for light loads to trigger slabs even from relatively low angle slopes. Be extra cautious near treeline where surface hoar is more likely to be preserved.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Be careful with low angle slopes that may not normally be a concern.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Wind Slabs

Storm and wind slabs continue to grow. These slabs may be particularly touchy in exposed lee (W-NE) and cross-loaded terrain.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: North, North East, East, South East, South.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Jan 25th, 2016 2:00PM